High power generators of sounds and ultra-sounds



July 24, 1956 R. LEVAVASSEUR 2,755,767

HIGH POWER GENERATQRS OF SOUNDS AND ULTRA-SOUNDS Filed July 9, 1952 N VE N TD R W? Lewd wa /431 HIGH POWER GENERATORS OF SOUNDS AND ULTRA-SOUNDS Robert Levavasseur, Marseille, France, assignor to Centre National de la Recherche Scientifique (C. N. R. 5.), Paris, France, a society of France Application July 9, 1952, Serial No. 297,830

Claims priority, application France July 10, 1951 2 Claims. (Cl. 116-137) High power sounds and ultra-sounds are more and more used in industrial processes, ultra-sounds being employed in liquids and both sounds and ultra-sounds in air and gases. In particular, sounds and ultra-sounds are used for the production of emulsions, for chemical treatments, homogenizing, sterilizing, killing certain kinds of insects, precipitating smokes (in particular for the manufacture of carbon black), precipitating dust and chemical fogs.

In some cases, for the treatment of liquids, use is made of ultra-sounds formed in air and acting on the liquid flowing in the form of a thin sheet.

Only the difliculty of producing high power generators of sounds and ultra-sounds prevented, up to now, the use on an industrial scale of these methods which have been found highly satisfactory in laboratories.

The object of the present invention is a generator which is very simple and easy to manufacture and makes it possible to obtain high sound and ultra-sound powers. Such a generator, of a purely mechanical nature, is static and does not include any part set in movement by an external force. It permits of obtaining acoustic powers as high as those supplied by a hooter. Contrary to sound pipes and whistles used for the production of sounds and ultrasounds as used up to this time, the size and therefore the power of which depend upon the frequency, the generator according to the present invention may have dimensions as great as possible, whatever be the frequency that is used.

A preferred embodiment of my invention will be hereinafter described with reference to the appended drawing, given merely by way of example. The only figure shows, by way of example and in axial section, an embodiment of a whistle made according to my invention.

The sound generator shown in the drawing is of the toroidal type. The toroidal whistle chamber 8 is of substantially circular cross section and its depth may be for instance equal to one half of the wave-length of the sound to be produced. This chamber is obtained by cutting on a lathe the side wall of a duralumin annular piece 9. The jet of air under pressure arrives into this toroidal chamber through the annular orifice 10 of nozzle 11 fed with compressed air from tube 12, through several orifices 13. The thin sheet from annular orifice 10 strikes the whistle edge 3 of chamber 8. Opposite chamber 8, there is provided an auxiliary chamber 20 formed in a piece 19 coaxial with piece 9. The edge 2 of auxiliary chamber 20 is at a greater distance from nozzle 11 than the whistle edge 3.

The adaptation of the acoustic impedances is obtained by the annular exponential horn formed by the two pieces nited States Patent O 2,755,767 Patented July 24, 1956 14 and 15, both of revolution about axis AB and starting from edges 2 and 3.

All the pieces which constitute this high power sound or ultra-sound whistle may be made on a lathe, which makes its manufacture particularly simple and economical.

The angle made by the air jet issuing from the annular orifice 10 with respect to the resonating chamber plays an important part from the point of view of efficiency. It is of a value of 20 (with respect to axis AB) in the case of a frequency of 12.000 p. s. The angular aperture of the nozzle ending in orifice 10 averages 14. The position of orifice 10 with respect to resonating chamber 8 requires a very accurate adjustment. This adjustment is obtained by moving piece 9 with respect to piece 16. Screw-threads 17 facilitate this adjustment, whereas screwthreads 18 serve to the fixation of piece 14.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and efficient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:

1. A generator of waves within the sonic and ultrasonic range which comprises, in combination, means forming a whistle resonating chamber open on one side and having a Whistle edge along said side, a nozzle fixed with respect to said means having a slot-shaped fluid outlet arranged to direct a thin fluid sheet along said open side of said chamber onto said whistle edge, means fixed with respect to said nozzle and said chamber forming an auxiliary chamber open opposite said first-mentioned chamber and located on the opposite side of said fluid sheet from said first mentioned chamber, said opening of said auxiliary chamber having two edges at least substantially parallel to said whistle edge, that of said two last mentioned edges which is farther from said nozzle being at a greater distance from said nozzle than said whistle edge, and a horn rigid with said means forming said chambers and said nozzle, the walls of said horns starting from said whistle edge and from said last mentioned edge of said opening of said auxiliary chamber edge respectively.

2, A generator of waves according to claim 1 in which the means forming the whistle resonating chamber and the means forming the auxiliary chamber are in the form of bodies of revolution coaxial with each other, whereby said chambers are of toroidal shape, the means forming the auxiliary chamber surrounding the means forming the whistle resonating chamber, said horn also being of revolution and coaxial with said means including an ogival inner portion carried by said first mentioned means, and a flaring portion carried by said second mentioned means.

References Cited in the file of this patent UNITED STATES PATENTS 1,515,471 Foley Nov. 11, 1924 1,881,211 McCune Oct. 4, 1932 2,142,184 Down Jan. 3, 1939 2,424,375 Van Allen July 22, 1947 2,528,026 Allen Oct. 31, 1950 2,570,081 Szczeniowski Oct. 2, 1951 

